Depends on what you wanna do with a 1/8th scale. You wanna bash it with the occasional race or go full blown race ? Kyosho, X-ray, TTR, Jammin, Mugen and Sportwerks are mainly aimed at racers. While the others seem more aimed toward the basher/part-time racer. The high dollar kits are more money, but durable more tunable and drive different on the track.
So, 580 for a XB8 kit in my opinion is worth the cashola.